The present technology relates to the assembly of an electronic device, and more specifically, to an electronic device assembled with an adjustable lens, a printed circuit board and a carrier frame supporting the printed circuit board and the lens.
Most if not all electronic devices include one or more printed circuit boards (PCBs). During assembly, the board(s) are screwed to or otherwise connected to a portion of the electronic device's housing or other boards within the housing. One type of electronic device is an imaging device, more generally referred to as a camera. An imaging device is generally used to inspect, locate and/or acquire an image of an object. For example, in manufacturing applications, imaging systems can be used to detect defects in a manufactured object by acquiring images of the object and using various types of image processing algorithms to analyze the images. Unlike traditional cameras that use film to capture and store an image, some imaging devices use various electronic, solid-state, and other devices including vision sensors, controllers, illumination devices, lenses, and the like.
Some imaging devices can include a housing with the solid state devices mounted to several rigid PCBs, with the rigid PCBs held in the desired configuration by the housing. One of the several rigid PCBs needs to be aligned with a lens, and the lens needs to be aligned with an opening in the housing. Connectors are used to connect the one or more of the PCBs together, which adds size, cost, assembly time, and possible areas for failure. The size of the housing is limited to the size of the various solid-state devices and the rigid PCBs used to support them.
Improvements have been made in the area of printed circuit boards for electronic devices. PCBs are now available in flexible form, and a hybrid of rigid and flexible, known as rigid-flex. The hybrid rigid-flex PCB generally consists of rigid and flexible substrates that are laminated together into a single structure. Another form of PCB is known as a rigidized flex construction, which is simply flex circuits that include stiffeners attached to provide support for the electronic components on the circuit board. A rigid-flex circuit typically has conductors on the rigid layers, which differentiates it from multi-layer circuits with stiffeners.
In some imaging devices, the lens can be threaded into the housing or a lens carrier to allow for adjustment of the focus of the lens. When the lens is threaded to allow for adjustment, there is always an amount tolerance or backlash between the lens thread and the mating thread of a lens carrier. This undesirable backlash can result in an shift of focus and in a tilted optical axis of the lens with respect to the optical axis of the imaging device. The shift of focus reduces image quality, and the reduced image quality is exacerbated with shorter focal lengths.
Attempts have been made to reduce backlash, but have only provided limited success, and tend to reduce the adjustability of the lens. Some configurations include using a helical spring positioned between the lens carrier and a spacer screwed to the threaded lens. In this configuration, as the lens is screwed in or out to adjust focus, the force applied by the spring changes. As the force applied by the spring changes, so does its ability to reduce the backlash. Other configurations have included using a retaining ring to apply a force to the lens. In this configuration, the retaining ring must be removed before the lens can be adjusted. When the retaining ring is replaced, its backlash reduction can vary from prior lens positions.
The electronic devices of the prior art have several disadvantages in not only the assembly process, but in the overall size and limits on the serviceability of rigid circuit boards, reliability of PCB connectors, and lens backlash. What is needed are systems and methods that use a carrier frame to support the PCBs for easy assembly and reduce or eliminate lens backlash, without the problems and drawbacks associated with prior configurations.